diff --git a/install_postfix_base.sh b/install_postfix_base.sh
index 51ac6dd..40b0b0a 100755
--- a/install_postfix_base.sh
+++ b/install_postfix_base.sh
@@ -84,18 +84,17 @@ blank_line() {
    fi
 }
 
-
-detect_os () {
+detect_os_1 () {
 
    if $(which lsb_release > /dev/null 2>&1) ; then
 
-      DIST="$(lsb_release -i | awk '{print tolower($3)}')"
-      DIST_VERSION="$(lsb_release -r | awk '{print tolower($2)}')"
-      DIST_CODENAME="$(lsb_release -c | awk '{print tolower($2)}')"
+      os_dist="$(lsb_release -i | awk '{print tolower($3)}')"
+      os_version="$(lsb_release -r | awk '{print tolower($2)}')"
+      os_codename="$(lsb_release -c | awk '{print tolower($2)}')"
 
-      if [[ "$DIST" = "debian" ]]; then
-         if $(echo "$DIST_VERSION" | grep -q '\.') ; then
-            DIST_VERSION=$(echo "$DIST_VERSION" | cut --delimiter='.' -f1)
+      if [[ "$os_dist" = "debian" ]]; then
+         if $(echo "$os_version" | grep -q '\.') ; then
+            os_version=$(echo "$os_version" | cut --delimiter='.' -f1)
          fi
       fi
 
@@ -103,14 +102,14 @@ detect_os () {
 
       . /etc/os-release
 
-      DIST=$ID
-      DIST_VERSION=${VERSION_ID}
+      os_dist=$ID
+      os_version=${VERSION_ID}
 
    fi
 
-   # remove whitespace from DIST and DIST_VERSION
-   DIST="${DIST// /}"
-   DIST_VERSION="${DIST_VERSION// /}"
+   # remove whitespace from os_dist and os_version
+   os_dist="${os_dist// /}"
+   os_version="${os_version// /}"
 
 }
 
@@ -157,7 +156,7 @@ fi
 
 blank_line
 echononl "Detect distribution/release of running OS.."
-detect_os  > /dev/null 2>&1
+detect_os_1  > /dev/null 2>&1
 if [[ $? -ne 0 ]]; then
    echo_failed
 else
@@ -1047,7 +1046,7 @@ fi
 ## -
 echononl "   Generate DH key length=512 \"/etc/postfix/ssl/dh_512.pem\""
 if [[ ! -f /etc/postfix/ssl/dh_512.pem ]]; then
-   if [[ $DIST_VERSION -gt 11 ]] ; then
+   if [[ "$os_dist" = "debian" ]] && [[ $os_version -gt 11 ]] ; then
       openssl dhparam -out /etc/postfix/ssl/dh_512.pem 512 > /dev/null 2>&1
    else
       openssl dhparam -dsaparam -out /etc/postfix/ssl/dh_512.pem 512 > /dev/null 2>&1
@@ -1058,7 +1057,7 @@ if [[ ! -f /etc/postfix/ssl/dh_512.pem ]]; then
       echo_failed
    fi
 else
-   if [[ $DIST_VERSION -gt 11 ]] ; then
+   if [[ "$os_dist" = "debian" ]] && [[ $os_version -gt 11 ]] ; then
       if $(grep -q -E "X9.42" /etc/postfix/ssl/dh_512.pem 2> /dev/null); then
          openssl dhparam -out /etc/postfix/ssl/dh_512.pem 512 > /dev/null 2>&1
          if [[ $? -eq 0 ]] ; then
@@ -1075,7 +1074,7 @@ else
 fi
 echononl "   Generate DH key length=1024 \"/etc/postfix/ssl/dh_1024.pem\""
 if [[ ! -f /etc/postfix/ssl/dh_1024.pem ]]; then
-   if [[ $DIST_VERSION -gt 11 ]] ; then
+   if [[ "$os_dist" = "debian" ]] && [[ $os_version -gt 11 ]] ; then
       openssl dhparam -out /etc/postfix/ssl/dh_1024.pem 1024 > /dev/null 2>&1
    else
       openssl dhparam -dsaparam -out /etc/postfix/ssl/dh_1024.pem 1024 > /dev/null 2>&1
@@ -1086,7 +1085,7 @@ if [[ ! -f /etc/postfix/ssl/dh_1024.pem ]]; then
       echo_failed
    fi
 else
-   if [[ $DIST_VERSION -gt 11 ]] ; then
+   if [[ "$os_dist" = "debian" ]] && [[ $os_version -gt 11 ]] ; then
       if $(grep -q -E "X9.42" /etc/postfix/ssl/dh_1024.pem 2> /dev/null); then
          openssl dhparam -out /etc/postfix/ssl/dh_1024.pem 1024 > /dev/null 2>&1
          if [[ $? -eq 0 ]] ; then
@@ -1103,7 +1102,7 @@ else
 fi
 echononl "   Generate DH key length=2048 \"/etc/postfix/ssl/dh_2048.pem\""
 if [[ ! -f /etc/postfix/ssl/dh_2048.pem ]]; then
-   if [[ $DIST_VERSION -gt 11 ]] ; then
+   if [[ "$os_dist" = "debian" ]] && [[ $os_version -gt 11 ]] ; then
       openssl dhparam -out /etc/postfix/ssl/dh_2048.pem 2048 > /dev/null 2>&1
    else
       openssl dhparam -dsaparam -out /etc/postfix/ssl/dh_2048.pem 2048 > /dev/null 2>&1
@@ -1114,7 +1113,7 @@ if [[ ! -f /etc/postfix/ssl/dh_2048.pem ]]; then
       echo_failed
    fi
 else
-   if [[ $DIST_VERSION -gt 11 ]] ; then
+   if [[ "$os_dist" = "debian" ]] && [[ $os_version -gt 11 ]] ; then
       if $(grep -q -E "X9.42" /etc/postfix/ssl/dh_2048.pem 2> /dev/null); then
          openssl dhparam -out /etc/postfix/ssl/dh_2048.pem 2048 > /dev/null 2>&1
          if [[ $? -eq 0 ]] ; then